Poly Trifluoroethylene Research Articles

Estimation of the work of adhesion between ITO and polymer substrates: a surface thermodynamics approach.

Indium tin oxide (ITO) is one of the most widely used semiconductor among transparent conducting oxides (TCOs) due to their electrical conductivity and optical transparency properties. Since the development of low temperature deposition methods, coating of ITO on polymer substrates especially for use in flexible electronics has been a popular topic. The existence of adequate adhesion strength between ITO and polymer is critical in producing a successful film. Nowadays, polycarbonate (PC), poly(methyl methacrylate) (PMMA) and polyethyleneterephtalate (PET) are frequently used as substrates for such coatings. However, there may be other polymeric alternatives that have a potential to be used for this purpose in the future. To evaluate these alternatives, work of adhesion (Wa) knowledge between ITO and polymers is necessary, and it has not been handled systematically previously. In this study, the interphase interaction parameters and Wa values between ITO and various polymers were calculated based on the Dupré, Fowkes and Girifalco-Good equations. PC, PMMA, PET, polystyrene (PS), polyphenylene sulfide (PPS), Nylon 66, polypropylene (PP), polyvinylchloride (PVC), styrene-butadiene rubber (SBR), high density polyethylene (HDPE), low density polyethylene (LDPE), polyvinyl acetate (PVAc), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polytrifluoroethylene (PTrFE) and polyperfluoroalkylethyl acrylate (PPFA) were considered as substrate material. Surface free energy (SFE) components calculated by acid-base, geometric mean and harmonic mean approaches for polymeric substrates were used during the calculations. In the present study, the polymers that can be used as substrates were evaluated in terms of adhesion ability to ITO, the significance of calculation methods on Wa values were also investigated simultaneously. It was determined that the Wa between ITO and polymer substrates was directly related with the total SFE value of the polymers.

NMR investigations of polytrifluoroethylene (PTrFE) synthesized by RAFT

Identification of the 1H, 19F, and 13C NMR signals of the end-groups of polytrifluoroethylene synthesized by RAFT polymerisation.

Local mechanical and electromechanical properties of the P(VDF-TrFE)-graphene oxide thin films

Recently, many organic materials, including carbon materials such as carbon nanotubes (CNTs) and graphene (single-walled carbon sheet structure) were studied in order to improve their mechanical and electrical properties. In particular, copolymers of poly (vinylidene fluoride) and poly trifluoroethylene [P(VDF-TrFE)] are promising materials, which can be used as probes, sensors, actuators, etc. Composite thin film of the copolymer P(VDF-TrFE) with graphene oxide (GO) were prepared by spin coating. The obtained films were investigated using piezoresponse force microscopy (PFM). The switching behavior, piezoelectric response, dielectric permittivity and mechanical properties of the films were found to depend on the presence of GO. For understanding the mechanism of piezoresponse evolution of the composite we used models of PVDF chain, its behavior in electrical field and computed the data for piezoelectric coefficients using HyperChem software. The summarized models of graphene oxide based on graphene layer from 96 carbon atoms C: with oxygen and OH groups and with COOH groups arranged by hydrogen were used for PVDF/Graphene oxide complex: 1) with H-side (hydrogen atom) connected from PVDF to graphene oxide, 2) with F-side (fluorine atom) connected from PVDF graphene oxide and 3) Graphene Oxide/PVDF with both sides (sandwich type). Experimental results qualitatively correlate with those obtained in the calculations.

Human Neuronal SHSY5Y Cells on PVDF:PTrFE Copolymer Thin Films

Here, we investigate the in vitro biocompatibility of polyvinylidenefluoride (PVDF)–polytrifluoroethylene (PTrFE) copolymer thin films using neuronal cells. The aim is to obtain an optimal capping layer material for hybrid bio‐organic electronic transducers based on organic electronic devices, which can be applied for bidirectional communication with the central nervous system. PVDF:PTrFE thin films were grown by spin coating and characterized by AFM. Human neuroblastoma SHSY5Y cells were used as neuronal model and their interaction with PVDF:PTrFE films was investigated in term of cell adhesion, proliferation, differentiation, and cytoskeleton organization. We show that PVDF:PTrFE thin films allowed standard SHSY5Y proliferation and neuronal differentiation, even if with reduced short‐term cell adhesion and spreading.

Effects of Absorbed Benzene on Relaxation Behavior of Polytrifluoroethylene

Relaxation behavior in polytrifluoroethylene (PTrFE) with varied crystallinity and swollen with benzene was investigated by mechanical and dielectric measurements. PTrFE showed the α, β, and β′ relaxation in decreasing order of temperature. The β relaxation observed around –20°C at 100 Hz was considered to consist of two components assigned to the amorphous and crystalline regions. The β′ relaxation found in a lower temperature region below –50°C was related to molecular motions around the defects of anomalous linkages such as head-to-head and tail-to-tail. In swollen PTrFE, the α relaxation due to the micro-Brownian motions of main chains shifted from 50°C to –10—0°C in mechanical measurements. The β relaxation for swollen samples decreased in intensity or vanished. This was interpreted by considering that the component assigned to the amorphous regions did not occur or was concealed by the α relaxation shifted to lower temperature. Relaxation behavior of the component assigned to the crystalline regions was revealed in swollen samples and related to reorientation of chains adjacent to the row vacancy defects at chain end.

Ferroelectric order and phase transition in polytrifluoroethylene

AbstractPolarization‐reversal currents and x‐ray profiles under a high dc field were measured on polytrifluoroethylene (PTrFE) samples prepared by melt crystallization at different cooling rates. The results for PTrFE were found to be analogous to those for copolymers of vinylidene fluoride and trifluoroethylene [P(VDF/TrFE)] with low VDF content. Slow‐cooled and quenched samples showed different x‐ray profiles but the same IR spectra. For the slow‐cooled samples, a polarization reversal was clearly observed as a peak in polarization current, offering evidence for ferroelectric order in PTrFE. The ferroelectric behavior was found to be unlike that of typical ferroelectric polymers. There are two processes in a polarization reversal, i.e., partial depolarization reversal, accompanied by crystalline phase transitions. It is noted that no ferroelectric order was observed for the quenched sample which, however, becomes pyroelectric by poling as revealed by our previous studies. We speculate on possible crystal structures of PTrFE based on the published structure models and the present results. The relation between the ferroelectricity and the previously reported pyroelectricity is also discussed.

Pyroelectricity in Oriented Polytrifluoroethylene

Poling of oriented polytrifluoroethylene (PTrFE) was found to produce pyroelectricity which showed anomalous behavior and formation conditions identical to those in unoriented samples. The pyroelectric activity in oriented PTrFE was greatly enhanced when the poling temperature was low but was reduced as the poling temperature was raised, contrary to the behavior of ordinary thermoelectrets. The enhancement of the pyroelectricity is attributed to a greater increase of the new crystalline region and to the orientation effect, which aligned the dipoles along the electric field. The reduction of the pyroelectricity is attributed to an increase in the degree of chain orientation, which aligns the polar axis parallel to the film plane. This behavior depended strongly on the state of the amorphous region from which the new crystalline region carrying the spontaneous polarization grew.

Ultrasonic studies of three fluoropolymers

The ultrasonic velocities and attenuations of poly(vinylidene fluoride), poly trifluoroethylene and polychlorotrifluoroethylene at 10 MHz from 170 to 300 K have been measured by the pulse echo-overlap and the pulse-height comparison methods, respectively. Discontinuities in the slopes of the velocity — temperature curves and concurrent sharp rises of attenuations were observed, and were identified with previously reported transitions. An analysis of the fractional changes in the corresponding temperature coefficients was made. The velocity data extrapolated to 0 K by Rao's rule were combined with presently available thermal data to yield the effective three-dimensional intermolecular force constants in the Tarasov model, and to confirm the existence of low-frequency vibrational modes contributing to the specific heat of polychlorotrifluoroethylene. The magnitude and temperature dependence of the elastic moduli and the Poisson ratio in relation to those of the velocities are also discussed.